Drip tube



' Feb. 15, 1955 s. R. BENT DRIP TUBE Original Filed Sept. 14. 1953 lllllllll INVEN TOR. ew fierz BY MW W ATTORNEYS.

Potent ed Feb DRIP TUBE George Russell Bent, Northbrook, 11]., a'sslgnor to Baxter Laboratories, lnc., Morton Grove, Ill., a corporation of Delaware Continuation of application Serial No. 379,991, st ternber 6Clalms. (Cl. 128-214) This application is a continuation of my application,

14,1953. Tliis application September 20, 195 Serial Serial No. 379,997, filed September 14, 1953 This invention relates to a drip tube, and more particularly, to a sight drip tube in which liquid drops may be counted during the administration of parenteral solutions,

and the like.

Considerable difiiculty has been encountered in the fabrication of drip tubes in that the inlet tube from which the drop falls is often not'fully centered within the tube and liquid tends to slide from the end of the inlet tube to a side wall of the main tube, thus preventing observation'of-the falling of the drop, while also obscuring the main tube. The problemis considerably aggravated.

when the inlet tube is made of plastic and when also theoutertube or main tube is made of plastic. Plastic tubes tendjto bend under compression, and in the assembly. of the parts, it is found that often the inner plastic tube tends to tilt towardone side wall of the main tube and thus cause the liquid to stream down the side wall ofthemain. be.

An object of the present invention is to provide a structure overcoming the above difiiculties and providing an accurately assembled drip tube in which the inlet tube is centered'to cause the drops to fall the full desired distance for observation. A further object is to provide a plastic tube having the characteristics described and in which the plasticv is very substantially strengthened through the use of fins in the upper portion of the main tube, which thus strengthen the tube while at the same time centering the inner or drop tube within the main tube. .A still further obje'ctis to combine a structure of a this character in a filter device. Other specific objects and advantages will appear as the specification proceeds.

The invention is shown, in a specific embodiment, by the accompanying drawing,'in whicht Figure l isa perspective view of a drip tube and connections; therefor embodying my invention; Fig. 2, an

' enlarged, tranverse, sectional view, the section being taken as indicated at line 2 --2.'of Fig. 1; Fig. 3, a view similar 1 to Fig. l but showing the initial bending of sectors of the 18m tube preparatory to forming the structure shown in Fig. 2; Fig. 4'. a'view similar to Fig. 3 but showing asecondstep following the'step shown in Fi 3; Fig. 5, abroken s eetioniil view, the sectionbeing t en as indicated at lines-5 of Fig.2; Fig. 6, a sectional detail view, the se'ction being taken as'indicated at line 6-6 of Fig. 2;

In the illustration given, a tube 10 formed of plastic,

or other suitable material, but preferably formed of a thermoplastic resin, isprovided at its upper end with a tube or tubes 11 for supplying liquid to the tube 10, and

at its-lower end is provided with an outlet communicating 1 with the drain tube 12. Since such structure is well known, a detailed description is believed unncessary.

Within the driptube 10, a filter 13 may be interposed. The filter maybe provided with a disc 14 having a cen- "tral aperture 15' thereinyand filter cloth or material 16 therebelow terminating in a closed, disc 17.

Near the upper'part of the tube 10 is the inlet tube .or drop tube 18'. This is the tube that gives trouble in .the assembly operation because of its tendency to tilt in one direction or another and to approach one of the side walls of the tube 1" so that the liquid streams from which may be counted. g

I have discovered thatif opposite sectors of the tube I iaoent sector the tube 18 fixedly within the main tube '10 while at the same time holding the tube 10 in fully round sition. As those in the trade fully know, there is a ten ency f for plastic tubes to sag in areas and lose their perfectly I cylindrical shape. By employing the fins 19, as illustrated, I find that the sagging tendency of the plastic can be overcome, while at the same time centeringthe inlbe iiabe or drop tube 18 within the main transparent to As above indicated, the process of forming the fins in the centering operation may beperformed by'first together, as illustrated in Fig. 4, the fusion pleted as illustrated in Fig. 2.

Any of the. plastics commonly employed and foun useful forthe forming of drip tubes may be employed."

For example, polyvinyl chloride, polyethylene, and similar well known plastics and thermoplastics may be "used for the purpose indicated.

To accomplish the new results indicated, it is important that there be at least three fins which are effective in spacing the inner tube 18. Two oppositely-disposed fins are not sufiicient, because they do notefiectively den ter the tube with respect to the side walls which extent! at right angles to the fins, and further, the main tube 10 may become flatter along one side-and thus approach the end of the inlet tube 18. l have found that three fins l9 which are substantially equally spaced will center the tube 18 while also keeping the main tube '10 substantially in the desired round position. Also, four, five, six,

or any number of fins may be employed for obtaining It may, therefore, be stated that the fins, to effect the new results described, must be at least;

the same result.

three in number.

In the operation of the device, a main plastic tube 10, whether round or partly flattened, may be assembled as shown in Fig. 1,-with an inner tube or drop tube 18 supported in a central spaced position by the use of three or more fins spaced about the tube. The spacing of the fins is not only effective in centering the tube 18, but

the tube along the side rather than forming distinct drops I 'tion of the 1 formed of flexible thermoplastic material.

also in distending the tube 10 about the inner tube 18, thus kteaping the outer tube relatively round and fully distend This improves the visibility of the drops from the tube 18, requiring that the drops fall the full length top of .the-

of the tube, or, at least, if a filter'is used, to the filter. At the same time, the fins 19 form relatively hardened ribs which strengthen the tube against, crushing. When the liquid flows through the connections 11 into the upper portion of tube 10, it passes into the drop tube or inner tube 18, forming drops as the liquid passes through the main tube 10. The nurse or doctor may count the drops so as to determine the weight of introducquid, etc. The liquid passes through 'the filter 16 and out through the drain tube. 12 tov ahollow hypodermic needle, through While, in t e foregoing specification, 1 have set forth a specific structure in considerable detail for the purpose of illustrating an embodiment of the invention, it will'be.

understood that such details of structure may be varied widely by those skilled in the art without departing from theI stiiiit of my invention.

c am:

1 A drip tube, comprising a transparent tube body I having in its upper portion an inlet tube and at its bottom fused withsaid inlet tube.

3. The structure of claim l,in which the fins are 4. A- drip tube, a flexible portions fused together to form -iins l.9,-- as illustrated in Figs. 2 and 4, that the fins will center 1 which the liquid is iutroduced into a about or utilized for some other purpose.

outer tube having sa substantially transparent portion,

and an inlet tube communicating with said transparent plastic portion and supported in centered relation within said outer tube, said outer tube having sector portions about said inner tube fused together to form radiating fins with their inner portions providing arcuate shoulders engaging said inner tube, said fins being at least three n number and forming a seal about said inner tube.

5. The structure of claim 4, in which the inner tube is also of flexible plastic material and is fused with the 10 moulder portions of said fins.

tively stiff fins centering said inlet tube within said firstmentioned tube.

No references cited. 

